You can't call yourself a true IT pro until you've visited at least one of the "holy sites" where computing history was made

If you really want to qualify as a member of the Geek Tribe, you have to make a pilgrimage to the holy land. Fortunately with high tech, there's not just one sacred site but dozens, says John Graham-Cumming, author of "The Geek Atlas," a guide to "128 Places Where Science & Technology Come Alive."

Graham-Cumming's guide book covers everything from where Newton's apple fell to the pub where Watson and Crick announced they'd unlocked the secret to DNA. He also has a handful of entries specific to computers.

"If you're a computer person, the three essential places to visit are the Computer History Museum in San Jose, Bletchley Park, and the London Museum of Science," says Graham-Cumming. "At the latter you can see a working model of Charles Babbage's Difference Engine, which they built using the tools available at the time. It's remarkable."

Those are hardly the only ones. We've identified the 12 most sacred places where IT enthusiasts can go to pay homage to the computing gods that passed before them -- or at least catch a peek at where some of the more exciting events in IT lore occurred. Fortunately, would-be pilgrims can do a lot of the traveling via the Web, saving wear and tear on the sandals and sackcloth.